The 6rd enhancement in pfSense was written by Ermal for the FreeBSD sources, but never made it to FreeBSD itself. It is a bit like the "shared forwarding" code that we wrote for OPNsense. The point is in these cases the project itself works on the feature and as an open source project releases the patches to the public.

Since we jumped to FreeBSD 11.0 long ahead of pfSense in January 2017, 6rd has been defunct because there have been no efforts to bring 6rd to 11.0 in pfSense yet. These efforts have in the last two months been made and I heard there are mostly working in the upcoming pfSense 2.4:

Jim Thompson, the owner of Netgate declined to comment. Nobody seems to know why the open source project has to go this route, a route they already went in 2014 before, which incidentally created OPNsense.

If you will, please ask them what their motivation is for not sharing with the open source world to grow together.

1. Howdy Jim, how is it going.2. Jim refuses to address the elephant in the room: where is the source for his open source.3. He is keeping this code away from FreeBSD, away from review and general adoption.4. OPNsense doesn't work with 6rd, no harm done either way.